Continuous metal-casting plant

ABSTRACT

A continuous metal-casting plant which includes a radial crystallizer and a secondary cooling zone of the ingot with guiding devices for the ingot. Said guiding devices form consecutively-arranged arc-shaped, curved and straight sections. The arc-shaped section has a radius of curvature and its length, including the length of the crystallizer, varies from 0.2 to 0.4 of the overall length of the plant. The length of the curved section, depending on the central angle included between the horizontal and the straight line drawn through the center of the crystallizer curvature and the junction point between said arcshaped and curved section is determined by the relation: WHERE L2 length of the curved section, m; Beta O CENTRAL ANGLE, RAD.; Ro radius of crystallizer curvature, m. The guiding devices of the curved section are arranged along a curve whose radius of curvature varies with the changes in the length of this section of the thickness of the ingot liquid phase and which is expressed by a natural equation WHERE A CURVE CONSTANT; H1 THICKNESS OF THE INGOT LIQUID PHASE, M; S1 present length of the curve arc, m.

Unite States atent [1 1 Gelfenbein et al.

45] Apr. 24, 1973 I CONTINUOUS METAL-CASTING PLANT [76] Inventors: Evgeny Jukhimovich Gelfenbein, ulitsa 40 let Oktyabrya, 28, kv. 51; Stanislav Evgenievich Karlinsky, ulitsa Kultury, 4, kv. 22; Vitaly Masimovich Niskovskikh, ulitsa Festivalnaya, 21, kv. 60; Georgy Lukich Khimich, ulitsa Lenina, 53, kv. 92, all of Sverdlovsk, USSR.

22 Filed: Apr.l,l971

21 Appl.No.: 130,413

[30] Foreign Application Priority Data June 18, 1970 U.S.S.R. v.1438559 [52] US. Cl ..164/282, 164/82 [51] Int. Cl. ..B22d 11/12 [58] Field of Search ..l64/82, 282, 283; 266/13 [56] References Cited UNITED STATES PATENTS Bungeroth et a1 164/82 Khimich et al. .164/283 X Primary ExaminerR. Spencer Annear Attorney-Holman & Stern [57] ABSTRACT A continuous metal-casting plant which includes a radial crystallizer and a secondary cooling zone of the ingot with guiding devices for the ingot. Said guiding devices form consecutively-arranged arc-shaped, curved and straight sections. The arc-shaped section has a radius of curvature and its length, including the length of the crystallizer, varies from 0.2 to 0.4 of the overall length of the plant. The length of the curved section, depending on the central angle included between the horizontal and the straight line drawn through the center of the crystallizer curvature and the junction point between said arc-shaped and curved section is determined by the relation:

12 :(1.:s--1.s) (T /20 0 where L; length of the curved section, m; B central angle, rad.; R radius of crystallizer curvature, in.

The guiding devices of the curved section are arranged along a curve whose radius of curvature varies with the changes in the length of this section of the thickness of the ingot liquid phase and which is expressed by a natural equation where 11 2 curve constant; 11, thickness of the ingot liquid phase, In; S, present length of the curve arc, m.

1 Claim, 1 Drawing Figure CONTINUOUS METAL-CASTXNG PLANT The present invention relates to continuous metalcasting plants and more specifically it relates to continuous metal-casting plants having a radial crystallizer.

The present invention is used most successfully for continuous casting of steel at a high speed.

Known in the art are continuous metal-casting plants comprising a radial crystallizer and a zone of secondary cooling with ingot guides where the ingot is gradually crystallized such metal-casting plants having consecutively arranged arc-shaped, curved and straight sections. While passing through the curved section, the ingot is gradually straightened. The curved section follows the shape of a parabola or clothoid or is made in the form of several successively-joined arcs with different radii. See, for example, French Pat. Nos. 1,387,621 and 1,423,330 C1.B 22d.

It is known that the most critical layers from the standpoint of the formation of internal defects during straightening of a liquid-core ingot are the layers located near the boundary between the solid and liquid phases. In this case the speed of their deformation is the governing factor. An increase in the casting speed leads to a higher speed of deformation of the ingot as the latter passes the curved section of the secondary cooling zone.

The secondary cooling zone in the known plants is arranged without taking into account the deformation speed of the ingot and the thickness of its liquid phase with the result that these plants do not provide for the optimum conditions of ingot formation and thus fail to produce high-quality ingots at high casting speeds.

The main object of the invention is to provide a continuous metal-casting plant which produces high-quality ingots at a high casting speed by creating the optimum conditions of ingot formation and deformation.

This object is achieved by providing a continuous metal-casting plant comprising a radial crystallizer and a secondary cooling zone with guiding devices for the ingot in which zone said ingot is gradually crystallized. The guiding devices form an arc-shaped section with a radius which is equal to the radius of curvature of the crystallizer, a curved section with a radius of curvature varying throughout its length, and a straight section, all these sections being arranged in succession. Length L, of the arc-shaped section, including the length of the crystallizer, is equal to 0.2 0.4 of the overall length L of the plant, length L, of the curved section depends on the central angle [3,, occupied by the arc-shaped section and varies within the limits determined by the relation where B, central angle between the horizontal and the straight line drawn through the center of curvature of the crystallizer and the junction point between the arc-shaped and curved sections, rad. and R, radius of curvature of the crystallizer, m.

The guiding devices are located on this curved section along the curve whose radius of curvature R depends on the changes in the thickness h of the ingot liquid phase along the length of said section, and which is expressed by a natural equation h R (1 L2 rsI where curve constant; and

S, present length of the curve arc, m. i

Due to this arrangement and to the above-mentioned relations, the crust of the ingot passing through the arc shaped section acquires a thickness which allows further deformation of the ingot to proceed without the formation of internal defects while the curve for the installation of the ingot guiding devices on the curved section ensures a lower speed of deformation of the ingot inner layers due to a uniform distribution of deformation of these layers throughout the length of the curved section.

Now the invention will be described in detail by way of example with reference to the accompanying drawing which illustrates an elementary diagram of the plant according o the invention.

The continuous metal-casting plant includes a radial crystallizer 1 with a certain radius of curvature R and a secondary cooling zone with guiding devices 2, e.g. rolls for the ingot 3. The crystallizer is intended for the primary cooling of molten metal 4 and forming the crust 5 of the ingot 3. The zone of secondary cooling serves for further gradual crystallization of the ingot, said zone consisting of the consecutively arranged areshaped section 6, curvedsection 7 and straight section 8.

The length L, of the arc-shaped section 6, including the length of the crystallizer, is selected so as to ensure crystallization of the ingot to 45 65 percent of its thickness at the end of this section. At such a thickness the crust 5 of the ingot 3 can withstand the simultaneous deformation under the effect of ferrostatic pressure and straightening of the ingot without the formation of internal defects.

The length of the section on which the ingot becomes covered with a crust can be calculated from the relation I= (S V)/(4K meters where:

S preset thickness of the ingot crust, cm;

V maximum casting speed, m/min;

K crystallization constant, cm/min.

It has been learned from experiments that the crystallization constant varies in the secondary cooling zone as follows:

Using the above-quoted values of ingot crystallization at the end of the arc-shaped section and of the crystallization constant K and calculating L, and L the overall length of the plant from formula (1) we obtain'.

This length of the arc-shaped section corresponds to the central angle [3,, included between the horizontal and the straight line connecting the center of curvature of the crystallizer with the end of the arc-shaped section.

The curved section 7 must ensure gradual and smooth straightening of the ingot 3 and a reduction in the deformation speed of the ingot internal layers 9, located near the boundary between its solid and liquid phases by uniform distribution of deformation of these layers along the entire length of the curved section.

The relative deformation E of the ingot layers located at a distance 11/2 from its axial line while said layers are unbent from the radius of curvature to the radius equal to infinity can be determined by the following expression:

lf deformation is uniformly distributed along the length of the curve are we find that (6/8) (h/2RS const where S distance from the given point on the curve to its end along the curve are (present length ofthe curve).

Hence, by expressing the present length of the curve in terms of the entire length L of the curved section, we will get the natural equation of this section according to the invention:

where a curve constant; it thickness of the ingot liquid phase (distance between the layers located near the boundary between the liquid and solid phases of the ingot),

S,= present length of the curve are from the beginning of the curved section.

The thickness h of the liquid phase of the ingot is a variable value throughout the length of the curved section.

At the boundary between the arc-shaped and curved sections it h,, R R and S 0; then the curve constant a (R l )/(h,)

where h thickness of ingot liquid phase at the beginning of the curved section.

lfwe denote (h )/(h,) m where h distance between the layers 9 of the ingot at the end of the curved section, then and the natural equation of the curve will take the form;

Now, using the known relation dS Rda we get:

The value of m is given assuming that the deformation speed of the ingot layers 9 is not higher than permissible with regard to the formation ofinternal defects in the ingot. On this condition m= 0.2 0.7. Then the length L, of the curved section will be The plant operates as follows: the molten metal 5 is fed into the crystallizer l where the ingot 3 is formed and covered with crust 5. Then the ingot passes without deformation through the first arc-shaped section 6 in the secondary cooling zone. At the end of the section whose length is determined by the above relation, the crust 5 of the ingot grows to such a thickness which allows further deformation of the ingot without the appearance of internal defects. Then the ingot is transferred to the next curved section 7, where it is gradually straightened from the curvature obtained in the crystallizer to the straight line and where the thickness of its crust is further increased.

The deformation speed of the ingot internal layers 9 located close to the boundary between the liquid and solid phases of the ingot is brought to a minimum by forming this section in accordance with the relations quoted above. This ensures the production of highquality ingots without internal defects at high casting speeds.

Final crystallization of the ingot 3 takes place in the straight section 8.

We claim:

1. A continuous ferrous-casting plant comprising: a radial crystallizer and a secondary cooling zone for formation of an ingot with guiding devices for said ingot, in which zone said ingot becomes gradually crystallized, said guiding devices forming three consecutivelyarranged sections comprising an arc-shaped section with a radius equal to the crystallizer radius R, of curvature and a length L including the crystallizer length, varying from 0.2 to 0.4 of the overall length L of the plant; a curved section whose length L depends on the central angle [3,, occupied by said arc-shaped section and is determined by the relation where [3,, central angle between a horizontal line drawn through the center of the crystallizer curvature and a straight line drawn through the junction point between said arc-shaped and curved sections, in radians, and R radius of crystallizer curvature, in meters, said guiding devices of said curved section being located along the curve whose radius R of curvature varies with the changes in the length of this section in the thickness h of the ingot liquid phase and which is expressed by a natural equation h R-a 2 where a curve constant, and S present length of the curve are, in meters, and a straight section, from 45-65 percent of the thickness of the ingot being crystallized by the end of said arc-shaped section so that the crystallized crust can withstand the ferrostatic pressure brought about by deformation in said arcshaped and curved sections, said curved section ensuring a gradual and smooth straightening by uniform distribution of deformation of the crystallized layers juxtaposed the solid liquid interface along the entire length of said curved section. 

1. A continuous ferrous-casting plant comprising: a radial crystallizer and a secondary cooling zone for formation of an ingot with guiding devices for said ingot, in which zone said ingot becomes gradually crystallized, said guiding devices forming three consecutively-arranged sections comprising an arcshaped section with a radius equal to the crystallizer radius Ro of curvature and a length L1, including the crystallizer length, varying from 0.2 to 0.4 of the overall length Lo of the plant; a curved section whose length L2 depends on the central angle Beta o occupied by said arc-shaped section and is determined by the relation where Beta o central angle between a horizontal line drawn through the center of the crystallizer curvature and a straight line drawn through the junction point between said arc-shaped and curved sections, in radians, and R0 radius of crystallizer curvature, in meters, said guiding devices of said curved section being located along the curve whose radius R of curvature varies with the changes in the length of this section in the thickness h of the ingot liquid phase and which is expressed by a natural equation where a curve constant, and S1 present length of the curve arc, in meters, and a straight section, from 45-65 percent of the thickness of the ingot being crystallized by the end of said arcshaped section so that the crystallized crust can withstand the ferrostatic pressure brought about by deformation in said arcshaped and curved sections, said curved section ensuring a gradual and smooth straightening by uniform distribution of deformation of the crystallized layers juxtaposed the solid liquid interface along the entire length of said curved section. 